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A year ago today, I was told something I thought was impossible — after three months in a knee brace as part of a research program, my previously fully ruptured anterior cruciate ligament (ACL) had healed itself naturally.
I tore my ACL skiing overseas (yes, I became a walking/limping cliche), and once I got home my physio told me about a novel program called the Cross Bracing Protocol.
The ACL runs diagonally through the middle of the knee, connecting the thigh bone to the shin bone, and is crucial to stabilising the joint.
In the last few years, research has proven that ACLs can, in fact, heal on their own, but the bracing protocol takes it one step further.
Just like a cast helps broken bones heal, the brace facilitates the healing of ruptured ACLs that otherwise wouldn't have healed at all, or might have healed poorly.
Given early results demonstrated 90 per cent of participants' ACLs healed at the three-month mark, it could revolutionise the way the injury is treated.
And it comes at an important time — Australia has one of the highest rates of ACL reconstructive surgery in the world and the incidence of ruptures is rising, particularly in children and women.
But, like any new medical breakthrough, there are questions about the long-term impact and the veracity of the research.
So, where did this idea come from and how does it work?
Patient number one
In 2014, Tom Cross was treating a colleague's 19-year-old daughter for an ACL rupture when she raised how desperate she was to avoid surgery, having watched two fellow netballers go through failed reconstructions.
Serendipitously, his orthopaedic surgeon dad, the late Mervyn Cross, was nearby doing his own rehab and suggested they brace her knee instead.
"He pulled the curtain back and said, 'Back in the 70s, we used to put plaster on people and bend their knee and some of them got better, others didn't — we never understood it because MRIs didn't exist,'" Dr Cross says.
"That was patient one and that worked."
It took another five patients over the next five years, all with successful healing, before Dr Cross decided to offer the novel bracing protocol to every patient who came to him with an ACL rupture.
"I'd sit down for one to two hours with every patient and I made sure I had plenty of time, and I started not charging them because it was [unpublished] research," he says.
"It was one patient at a time, most people would say, 'No, I'm not doing this, this is madness.'
"But there were some pioneering patients that said, 'I'll give it a go. I'd rather do this first, and surgery second if I need it.'"
Currently, more than 680 patients have felt that way — including myself, patient 293.
How does ACL bracing work?
In a nutshell, the idea is to treat the ACL like an acute fracture — it needs to be treated quickly and the two ends of the ligament, the "stumps", need to be brought as close together as possible to optimise healing.
Ideally, patients are braced five to 10 days after their injury, with a hard limit of 21 days — I was cutting it fine at day 18.
Tom and Mervyn Cross's theory is that in the first few weeks of the brace, the best position to encourage healing is a 90-degree angle.
After that, the range of movement of the knee is slowly increased until it's straight again.
How long you're in the brace (six, eight or 12 weeks) depends on the severity of your tear and any other injuries to your knee. I ended up in the brace for 12 weeks, four with my knee locked at 90 degrees and on crutches for eight.
(If that sounds like the end of the world I can tell you it was surprisingly not as hard as I thought it'd be.)
Participants also have to take a blood thinner to reduce the risk of Deep Vein Thrombosis (DVT) while the injured leg is out of action.
You're also given a week-by-week exercise guide to limit the amount of muscle loss and, once the healing period is over, work on increasing the range of movement.
It's a nervous wait until the three-month MRI to find out whether it worked, followed by more rehab to build back muscle that's been lost.
Importantly, it doesn't mean you can't have surgery afterwards, or down the line if the healing is unsuccessful or not the quality you need.
What are the results?
Even though almost 700 people have been braced, the first research published on the protocol in June 2023 only looked at the initial 80 participants.
It found that at the 12-week mark, 90 per cent of ACLs had healed.
Dr Cross says that figure has improved slightly, with roughly 94 per cent of participants in the series achieving some kind of heal (more on types of heals in a moment).
So far, patients' ages range from nine years old to those in their 70s.
In a big step forward for the bracing treatment, researcher Stephanie Filbay and her team at the University of Melbourne have been awarded more than $1.7 million to run a clinical trial comparing patient outcomes and treatment costs between early ACL surgery and the Cross Bracing Protocol.
It's hoped the trial will be up and running later this year.
In the meantime, as the number of participants continues to grow, Dr Cross and the others involved in the current research have got better at identifying which ACL ruptures are most likely to heal.
Who is it right for?
Jane Rooney, a researcher at Swinburne University and a specialist sports and exercise physiotherapist, works with Dr Cross on the bracing research and says it's important to note the treatment isn't for everyone.
"Certainly in our case series, there are still patients who we referred on for ACL reconstruction," she says.
"But it just gives people another option if they are appropriate for the Cross Bracing Protocol."
As Dr Cross explains, how much force was going through your knee when you tore your ACL is a big factor in whether the brace will or won't work.
In short, the more force — e.g. tackled during a top-grade rugby game — the more traumatic the injury and the less likely the bracing protocol is for you.
"In my experience, in the last five years, I've probably looked at 1,200 to 1,400 MRIs and 50 to 60 per cent of them I refer to surgeons because I believe [the ACL] is too profoundly hurt and I want the best for the patient to get a good healing outcome," he says.
"And the 40 to 50 per cent who we offer and who embrace this treatment, they heal according to where they are on the spectrum [of ACL injury]."
That "spectrum" is another crucial point both Dr Rooney and Dr Cross want people to understand — just like ACL tears are on a spectrum of severity, there's also a spectrum of healing.
The protocol breaks ACL healing results into five categories:
- 1.Gold medal — full thickness and fully taut, aka you have your old ACL back
- 2.Silver medal — full thickness but elongated
- 3.Bronze medal — reduced thickness but taut
- 4.Off the podium — reduced thickness and elongated
- 5.No healing at all
I was lucky enough to get a "gold medal heal" which Dr Cross also describes as "the time machine patient, there's your ACL back fully healed".
But even those who didn't have a top-quality heal still reported equal or better patient outcomes than those who had ACL reconstructive surgery.
Healing for individual needs
Dr Rooney says the type of heal people may need comes down to the physical activities they want to be able to do.
"What we're finding is that not all ACLs have to heal the same to be functional for that individual," she says.
"If you're a 50-year-old woman who walks around the block once a day, you may not need a 'gold medal' heal to continue to do that.
"The heals can be variable, but sometimes, for some people, any sort of heal is better than none."
As Dr Rooney points out, that may be particularly important for children whose bones are still growing, making surgery more challenging.
"Even if you go into the brace and get a 'bronze' or longer heal, if it gets you through to when you can have an adult reconstruction, that's good," she says.
Issue raised with MRI results, research
While there are several advantages to the bracing protocol, it's not without its downsides, including:
- It carries a risk of DVT (mitigated with a blood thinner),
- For women, the blood thinner can make menstrual cycles heavier,
- Muscle wastage is inevitable on the injured leg (mitigated with physiotherapy) and,
- Some people struggle with the general discomfort of being strapped in 24 hours a day
The protocol also has its critics in both the physiotherapy and orthopaedic surgery communities.
As well as the obvious lack of long-term data on the impact of bracing, questions have also been raised about whether the ACLs healed through the protocol were ever fully ruptured.
Dr Cross strongly refutes this, saying all patients to date have had ruptured ACLs as evidenced in individual radiologist reports and confirmed by his expert assessment.
Some surgeons have raised issues with the way the research is being conducted, saying the results have been undermined because it isn't a randomised control trial.
Others, like president of the Australian Knee Society and orthopaedic surgeon Myles Coolican, are tentatively supportive.
"You can understand that it isn't going to be a chosen treatment for a lot of people for a variety of reasons," he says.
"The concept of healing the ACL is not totally foreign, but healing simply by putting the knee in a brace is really kind of right out of left field.
"It's really quite different and most people would be sceptical about that, most surgeons would."
Dr Coolican is working with Dr Cross to make the protocol something more doctors could potentially roll out, and establish "rigorous" tests on all patients, not just those with successful outcomes.
"It has enough credibility to be assessed properly," Dr Coolican says.
"I think that most of us who are sceptical would say, 'It's unlikely to be a good outcome for all patients but it might work for some.'"
Dr Cross accepts the criticism about the lack of independent or randomised trials, but argues starting a new treatment method "is incredibly hard".
"[The bracing protocol] is not unsafe, and doctors are allowed to offer a new treatment based on their medical knowledge of anatomy physiology," he says.
"A lot of things in medicine start this way [because] you need a lot of money to do a really rigorous scientific study."
Future hopes for the brace
For now, Dr Cross is heartened by the growing interest in the bracing protocol and the continued willingness of people to give it a go.
He's hopeful that as the data set grows and more research is published, the treatment method will become widely available and, ultimately, become embedded in the management of ACL injuries.
"The biggest motivating things for me have been helping people who have no access to surgery, uninsured people, people around the planet in impoverished areas," Dr Cross says.
"In the developing world, where indeed they may not even have an MRI, you could enact this treatment and help a lot of people get knee stability.
"Equally, the young children who suffer ACL injury motivates me … because the children who do their ACL have got 90 years to suffer the morbidity of that injury.
"If you have the chance to manage them non-surgically and heal their ACL, why not take that chance."